Wheel bearing apparatus supports a vehicle wheel and freely rotationally supports a wheel hub for mounting a wheel via a double row rolling bearing is used for a driving wheel and a driven wheel. For structural reasons, the inner ring rotation type is used for the driving wheel and both the inner ring rotation type and the outer member rotation type are used for the driven wheel. There are four generation types of wheel bearing apparatus. The first generation type has a wheel bearing including a double row angular contact ball bearing, etc., fit between a knuckle, forming part of a suspension apparatus, and a wheel hub. The second generation type has a body mounting flange or a wheel mounting flange directly formed on the outer circumference of an outer member. The third generation type has one inner raceway surface directly formed on the outer circumference of a wheel hub. The fourth generation type has inner raceway surfaces formed on the outer circumferences, respectively, of a wheel hub and an outer joint member.
Angular contact ball bearings with an inner ring and an outer member (outer ring) formed by pressing a steel plate is known. For example, FIG. 16 shows an angular contact ball bearing 100 used in a magnetic hard disc device. An outer member 101 and a pair of inner rings 102, 103 are formed by pressing or rolling stainless steel plates.
The outer member 101 is formed substantially at its center with an annular projection 101a projecting radially inward. Outer raceway surfaces 101b, 101c are at either side of the annular projection 101a. The outer member 101 is fit into an aperture of a housing 104 and axially positioned with a flange 101d formed at its one end abutted against the end face of the housing 104. An annular recess 101a, formed by the inner circumferential surface, and the outer circumferential surface of the outer member 101, corresponding to the annular projection 101a, is filled with adhesive to secure the outer member 101 in place.
On the other hand, the inner rings 102, 103 are fit into the outer member 101. Axially outer ends of the inner rings 102, 103 are formed with curved shoulders 102a, 103a, respectively. The curved shoulders 102a, 103a are formed with inner raceway surfaces 102b, 103b, respectively. Double row balls 106, 106 are arranged between the inner raceway surfaces of the inner rings 102, 103 and the double row outer raceway surface 101b, 101b. They are held by cages 107, 107 in each row.
Fitting portions 102c, 103c, to be clearance fit onto a shaft member 105, are formed on the inner circumferences of the inner rings 102, 103, respectively. After the inner rings 102, 103 having been clearance fit onto the shaft member 105, a cylindrical weight 109, having a constant weight, is laid on the curved shoulder portion 102a of one of the inner rings 102. The curved shoulder portion 103a of the other inner ring 103 is pressed against the flange portion 105a of the shaft member 105 via balls 106 by weight 109. Thus, a suitable pre-load is applied to the angular contact ball bearing.
After completion of the clearance fit, a gap between the curved shoulder 102a of one inner ring 102 and the shaft member 105 is filled with adhesive 110. Thus, one inner ring 102 is prevented from slipping off from the shaft member 105. Also, the other inner ring 103 is prevented from slipping off from the shaft member 105 by its flange 105a. (Japanese Laid-open Utility Model Publication No. 1835/1994)
If the angular contact ball bearing 100, with the outer member 101 and the inner rings 102, 103 formed of steel plates by pressing, is used with seals, it is necessary to mount any seals in annular openings formed between the outer member 101 and the inner rings 102, 103. This not only increases the number of parts but significantly modifies the structure to provide spaces for the seals. Thus, this increases manufacturing cost, weight and size.